O.K. I think I need a little help here. I'm winding down my first day on Optifast. I've had 4 of my 5 shakes since this morning. I have a headache, some nausea, not to mention that I just want to lie down. My hunger pangs actually hurt. I'm drinking as much as I can, but 60 minutes of exercise is out of the question. Is this what it's going to be like! Has anybody else felt like this? Should I continue ? Will this pass? I did not expect this!